Stem-like and non-stem human pancreatic cancer cells distinguished by morphology and metastatic behavior

We report here that XPA1 human pancreatic cancer cells are dimorphic. After injection in the spleen, XPA1 cells isolated from the primary tumor in the spleen were predominantly round; while cells isolated from the resulting liver metastasis and ascites were comprised of both round- and spindle-shaped cell types. Cancer cells previously grown in the spleen and re-implanted in the spleen developed large primary tumors in the spleen only. Cancer cells isolated from liver metastasis and re-transplanted to the spleen resulted in a primary tumor in the spleen and liver metastasis. Cancer cells derived from ascites and re-transplanted to the spleen developed primary tumors in the spleen and distant metastasis in the liver, lung, and diaphragm in addition to ascites formation. Spindle and round cells were differentially labeled with fluorescent proteins of different colors. After co-injection of the two cell types in the spleen, cells were isolated from the primary tumors, liver metastasis, and ascites and analyzed by color-coded fluorescence microscopy and fluorescence-activated cell sorting (FACS). No significant differences between the percentages of spindle-shaped and round cancer cells in the primary tumor and the liver metastasis were observed. However, spindle-shaped cancer cells were enriched in the ascites. One hundred percent of the spindle-shaped and round cancer cells expressed CD44, suggesting that morphology and metastatic behavior rather than CD44 expression can distinguish the stem-like cells of the XPA1 pancreatic cancer cell line. The spindle-shaped cancer cells had the greater capability for distant metastasis and ascites formation, suggesting they are stem-like cells, which can be readily targeted for therapy.

Upregulation of thrombospondin-1 and angiogenesis in an aggressive human pancreatic cancer cell line selected for high metastasis

Pancreatic cancer remains a leading cause of death despite its relatively low incidence. As in many other solid tumors, angiogenesis is critical to the growth and metastasis of this cancer. Through serial in vivo passages in mice, we have developed a highly aggressive variant of human pancreatic cancer cell line XPA-1 which shows more rapid primary tumor growth, faster time to metastasis, and more rapid lethality than the parental cell line. The high-metastatic variant developed a much denser tumor vasculature early during growth within the pancreas. Interestingly, examination of the in vitro growth of this aggressive variant yielded no significant difference from the parental cell line. Real-time PCR evaluation of genes involved in angiogenesis revealed a 24-fold increase in Thrombospondin-1 expression in cells derived from the high-metastatic variant when compared with the parental cell line. These findings provide direct evidence that elevated capability for angiogenesis, mediated by specific changes in gene expression, can lead to a large increase in cancer aggressiveness and resulting metastasis. These findings have important implications for the treatment of metastatic disease.

Real-time imaging of tumor-cell shedding and trafficking in lymphatic channels

In the present report, we show real-time imaging of cancer cell trafficking in lymphatic vessels. Cancer cells labeled with both green fluorescent protein (GFP) in the nucleus and red fluorescent protein (RFP) in the cytoplasm or with GFP only or RFP only were injected into the inguinal lymph node of nude mice. The labeled cancer cells trafficked through lymphatic vessels where they were imaged via a skin flap in real time at the cellular level until they entered the axillary lymph node. The bright fluorescence of the cancer cells and the real-time microscopic imaging capability of the Olympus OV100 small-animal imaging system enabled imaging of the trafficking cancer cells in the lymphatics. Using this imaging strategy, two different cancer cell lines, one expressing GFP and the other expressing RFP, were simultaneously injected in the inguinal lymph node. Fluorescence imaging readily distinguished the two color-coded cell lines and their different abilities to survive in the lymphatic system. Using this imaging technology, we also investigated the role of pressure on tumor-cell shedding into lymphatic vessels. Pressure was generated by placing 25- and 250-g weights for 10 s on the bottom surface of a tumor-bearing footpad. Tumor cell fragments, single cells, and emboli shed from the footpad tumor were easily distinguished with the labeled cells and OV100 imaging system. Increasing pressure on the tumor increased the numbers of shed cells, fragments, and emboli. Pressure also deformed the shed emboli, increasing their maximum major axis. Imaging lymphatic trafficking of cancer cells can reveal critical steps of lymph node metastasis.

Imaging of nucleolar dynamics during the cell cycle of cancer cells in live mice

The synthesis and assembly of ribosomal subunits take place in the nucleolus. The nucleolus forms in the nucleus around the repeated ribosomal gene clusters and undergoes cyclic changes during the cell cycle. Although the nucleolus is easily visualized by light microscopy of cells in vitro, the nucleolus has not been imaged in cells in vivo. We report here development of a mouse model to visualize the nucleolus cycle of cancer cells in live mice. HT-1080 human fibrosarcoma cells were labeled in the nucleus with histone H2B-GFP and with retroviral RFP in the cytoplasm. The nucleolus was visualized by contrast to the fluorescence of GFP expressed in the nucleus. HT-1080 dual-color cells were seeded on the surface of a skin-flap of nude mice. The inside surface of the skin-flap was directly imaged with a laser scanning microscope 24 hours after seeding. The nucleoli of the cancer cells were clearly imaged in real-time. The appearance of the nucleoli changed dramatically during the cell cycle. During mitosis, the nucleolus disappeared. After mitosis, the nucleoli decreased in number and increased in size. The nucleolus appears to have a major role in cell cycle regulation. Nucleolar imaging could be used for more precise determination of cancer-cell position in the cell cycle in vivo.

Visualization of nascent tumor angiogenesis in lung and liver metastasis by differential dual-color fluorescence imaging in nestin-linked-GFP mice

Nestin regulatory-element-driven green fluorescent protein (ND-GFP) transgenic mice highly express GFP in proliferating endothelial cells and nascent blood vessels. In the present study, we visualized angiogenesis in experimental lung and liver metastases by GFP imaging in the ND-GFP transgenic mice. The murine melanoma cell line, B16F10 expressing red fluorescent protein (RFP), was injected i.v. in ND-GFP mice. ND-GFP was highly expressed in proliferating nascent blood vessels in the tumors that developed in the lung after tail vein injection, and in the tumors that developed in the liver after portal vein injection of RFP-expressing melanoma cells. Liver metastasis and angiogenesis were imaged intravitally. Doxorubicin significantly decreased metastatic angiogenesis in the liver. These results demonstrate a new imageable model of angiogenesis in metastasis in the liver and the lung. This new model should enable further understanding of the onset of angiogenesis in metastasis and its effect on metastatic growth. The model will serve as a unique screen for inhibitors of angiogenesis of metastatic tumors. The fact that liver-metastasis angiogenesis can be imaged in the live animal enables real-time studies of the effect of angiogenesis inhibitors.

Dual-color imaging of nascent angiogenesis and its inhibition in liver metastases of pancreatic cancer

As previously shown, the stem cell marker nestin is expressed in nascent blood vessels in transgenic nestin-driven green fluorescent protein (ND-GFP) nude mice. This mouse model was recently utilized to evaluate angiogenesis in primary tumors in an orthotopic model of pancreatic cancer. In the present study, nascent angiogenesis of pancreatic cancer liver metastasis in the ND-GFP transgenic nude mice after splenic injection of low-passage xPA-1 human pancreatic cancer cells expressing red fluorescent protein (RFP) was visualized by dual-color fluorescence imaging. ND-GFP was highly expressed in proliferating endothelial cells and nascent blood vessels in the growing liver metastasis. Immunohistochemical staining showed that CD31 co-localized in ND-GFP-expressing nascent blood vessels. The density of nascent blood vessels in the tumor was readily quantitated. Gemcitabine significantly decreased the mean nascent blood vessel density in the pancreatic liver metastases. In conclusion, the dual-color model of the ND-GFP nude mouse with RFP-expressing pancreatic cancer liver metastases, enabled the simultaneous visualization and quantitation of nascent angiogenesis and its response to angiogenesis inhibitors. This model will be useful for understanding the mechanism of angiogenesis of pancreatic cancer liver metastasis and for the discovery of effective new inhibitors of this process.

Chirurgische Behandlung benigner Läsionen und Strikturen der Gallenwege

Benign strictures of the biliary ducts are treated surgically in 90% of cases. Usually they are caused by trauma to the choledochous duct during gallbladder operations. Younger patients are frequently affected and, particularly if the strictures go untreated, can suffer from secondary complications such as cholangitis or secondary biliary cirrhosis with the serious dangers of portal hypertension and even hepatic failure and death. Although immediate treatment by end-to-end anastomosis has sometimes been described, this method is reasonable only for smooth cuts to the choledochous duct. Good long-term results have been achieved in 86% of cases with Roux-en-Y hepaticojejunostomy. In general, the best way to avoid complications is the all-important surgical maxim of correct indication for the primary operation. The best course is to limit the decision for surgery to symptomatic gallstones.

Dual-color imaging of nascent blood vessels vascularizing pancreatic cancer in an orthotopic model demonstrates antiangiogenesis efficacy of gemcitabine

BACKGROUND

The stem cell marker nestin recently has been shown to be expressed in nascent blood vessels in nestin-driven green fluorescent protein (ND-GFP) transgenic nude mice.

MATERIALS AND METHODS

In the present study, we visualized by dual-color fluorescence imaging tumor angiogenesis in the ND-GFP transgenic nude mice after orthotopic transplantation of the MIA PaCa-2 human pancreatic cancer line expressing red fluorescent protein. Mice were treated with gemcitabine at 150 mg/kg/dose on days 3, 6, 10, and 13 after tumor implantation. At day 14, mice were sacrificed and mean nascent blood vessel density and tumor volume were calculated and compared to control mice.

RESULTS

Nestin was highly expressed in proliferating endothelial cells and nascent blood vessels in the growing tumor. Results of immunohistochemical staining showed that CD31 co-localized in ND-GFP-expressing nascent blood vessels. The density of nascent blood vessels in the tumor was readily quantitated. Gemcitabine significantly decreased the mean nascent blood vessel density in the tumor as well as decreased tumor volume.

CONCLUSION

The dual-color model of the ND-GFP nude mouse orthotopically implanted with RFP-expressing pancreatic tumor cells enabled the simultaneous visualization and quantitation of tumor angiogenesis and tumor volume. These results demonstrated for the first time that gemcitabine is an inhibitor of angiogenesis as well as tumor growth in pancreatic cancer. The results have important implications for the clinical application of gemcitabine in this disease.

The role of interventional radiology for complications of cholecystectomy

This report summarizes diagnostic and therapeutic radiologic procedures in 45 patients who suffered major complications from cholecystectomy. Complications were divided into (1) bile duct injury or ligation and (2) a variety of pathologic fluid collections. Specific lesions were bile duct injury (n = 6), accidental bile duct ligation (n = 12), ductal stricture (n = 12), abscess (n = 11), biloma (n = 7), hematoma (n = 5), infected pancreatic pseudocyst (n = 3), and stones (n = 2). Presenting problems were sepsis, jaundice, and intermittent cholangitis. The patients underwent 104 interventional radiologic procedures including 29 percutaneous transhepatic cholangiograms, 21 percutaneous biliary drainages, 12 balloon dilatations of strictures, drainage of 11 abscesses, 8 bilomas, 5 hematomas, and 3 pancreatic pseudocysts. Stones were removed by baskets in 2 patients; 12 pressure and perfusion studies were performed. One hundred of 104 procedures were successful; there was one failed biliary drainage, one unsuccessful stricture dilatation, one unsuccessful hematoma drainage, and one recurrent biloma. Thirty patients were spared another operation. The percutaneous procedures were beneficial although not curative in 14 of 15 patients who underwent reoperation; in those patients the procedures helped to establish a diagnosis, improve the patient's preoperative status, or serve as a landmark for the surgeon to locate and repair the ligated or injured duct. One patient died after reoperation, a 2.2% mortality rate. Sectional imaging studies combined with interventional radiologic procedures help to diagnose promptly and effectively treat major complications of cholecystectomy. These interventional procedures either cure the complication and obviate reoperation or aid the surgeon by relieving sepsis and jaundice before reoperation and providing an intraoperative guide for bile duct reconstruction. (SURGERY 1990;W7:632–8.)

An evidence-based approach to the diagnosis and staging of pancreatic cancer

Technology has revolutionized the diagnosis and staging of pancreatic malignancy. Previously, staging of disease was accomplished by exploratory laparotomy. Now, however, tumor size, lymph node and vascular involvement and the presence of metastases can be reliably assessed prior to operation using a widely available series of diagnostic tests, facilitating a preoperative assessment of tumor resectability. Appropriate use of these tests often spares patients with unresectable disease the need for operative intervention. As part of our staging algorithm we routinely employ a combination of clinical suspicion, a high-resolution helical CT scan and a serum CA 19-9 level. Endoscopic ultrasonography is useful in the patient in whom CT findings are equivocal, or in whom a tissue diagnosis is desired. Laparoscopy is reserved for patients with suspected advanced disease despite imaging findings to the contrary. Using this strategy, pancreatic malignancy may be diagnosed as expeditiously and as cost-effectively as is possible given current technology.

Gastrointestinal Stromal Tumors Express ras Oncogene

BACKGROUND

Gastrointestinal stromal tumors (GISTs) constitute the largest category of nonepithelial neoplasms of the gastrointestinal tract. Histologically, they have a spindle cell appearance but stain by immunohistochemistry for the proto-oncogene, c-kit (CD117). There is some evidence that phosphorylation of these receptors leads to a cascade that may activate the ras/mitogen-activated protein kinase pathway, which may, in turn, allow other oncogenes to become active.

HYPOTHESIS

Immunohistochemical staining pattern of GISTs will aid in their differentiation from other spindle cell tumors and predict clinical outcome in patients.

DESIGN AND SETTING

Retrospective review of patient records and paraffin block specimens of spindle cell tumors.

PATIENTS

We have identified 65 patients with spindle cell tumors of the gastrointestinal tract at our institution in the past 10 years. Tumors were diagnosed by their morphology as leiomyomas, leiomyoblastomas, or leiomyosarcomas.

MAIN OUTCOME MEASURES

CD117 and ras p21 were stained by immunohistochemistry on formalin-fixed, paraffin-embedded sections of normal and tumor tissues.

RESULTS

Of the 65 patients, there were 23 patients diagnosed as having GIST confirmed by CD117 expression and 42 patients without GIST. Gastrointestinal stromal tumor samples of 17 (77%) of 22 patients stained positive for ras protein compared with 0 of 27 patients with leiomyomas (P<.001).

CONCLUSIONS

To our knowledge, this study is the first to demonstrate that GISTs stain positive for ras p21. This molecular trait may be a useful diagnostic tool in addition to the c-kit (CD117) to separate GISTs from leiomyomas and leiomyosarcomas. In the future, ras inhibitors may potentially be a therapeutic to treat GISTs.

Real-time in vivo dual-color imaging of intracapillary cancer cell and nucleus deformation and migration

The mechanism of cancer cell deformation and migration in narrow vessels is incompletely understood. In order to visualize the cytoplasmic and nuclear dynamics of cells migrating in capillaries, red fluorescent protein was expressed in the cytoplasm, and green fluorescent protein, linked to histone H2B, was expressed in the nucleus of cancer cells. Immediately after the cells were injected in the heart of nude mice, a skin flap on the abdomen was made. With a color CCD camera, we could observe highly elongated cancer cells and nuclei in capillaries in the skin flap in living mice. The migration velocities of the cancer cells in the capillaries were measured by capturing images of the dual-color fluorescent cells over time. The cells and nuclei in the capillaries elongated to fit the width of these vessels. The average length of the major axis of the cancer cells in the capillaries increased to approximately four times their normal length. The nuclei increased their length 1.6 times in the capillaries. Cancer cells in capillaries over 8 microm in diameter could migrate up to 48.3 microm/hour. The data suggests that the minimum diameter of capillaries where cancer cells are able to migrate is approximately 8 microm. The use of the dual-color cancer cells differentially labeled in the cytoplasm and nucleus and associated fluorescent imaging provide a powerful tool to understand the mechanism of cancer cell migration and deformation in small vessels.

Real-time whole-body imaging of an orthotopic metastatic prostate cancer model expressing red fluorescent protein

BACKGROUND

We describe here, a whole-body imageable spontaneous metastatic model of human prostate cancer developed by surgical orthotopic implantation (SOI) and visualized by red fluorescent protein (RFP) expression.

METHODS

Human prostate cancer PC-3 cells were transduced with the pLNCX2-DsRed-2-RFP retroviral vector containing the RFP and neomycin-resistance genes. A stable RFP-expressing PC-3 clone was selected in 800 microg/ml G418 in vitro and injected subcutaneously in nude mice. Stable high-level expression of RFP was maintained in the subcutaneously-growing tumors. To utilize RFP expression for metastasis studies, fragments of the subcutaneously-growing tumor, which were comprised of RFP-expressing cells, were implanted by SOI in the prostate of nude mice.

RESULTS

Primary tumor growth, progression, and subsequent lymphatic metastases were visualized in live, intact animals in real time by whole-body RFP fluorescence imaging. In total, 100% of the experimental animals developed lymphatic metastasis, the growth of which was monitored in real time by whole-body imaging. The aggressive lymphatic metastasis in this model reflects one of the major metastatic routes of prostate cancer in human patients. Intravital RFP imaging visualized single cancer cells in the lung and bladder. Open RFP imaging at autopsy visualized extensive primary growth and highly disseminated lymph-node metastases.

CONCLUSIONS

The long-wavelength emission of RFP enabled high sensitivity and resolution of microscopic tumor growth using appropriate imaging techniques. The model should be useful for the real-time evaluation of novel therapeutics for metastatic prostate cancer.

Color coding cancer cells with fluorescent proteins to visualize in vivo cellular interaction in metastatic colonies

We report here in vivo visualization of cancer cell interaction using stable sublines of green fluorescent protein (GFP)- and red fluorescent protein (RFP)-expressing HT-1080 human fibrosarcoma cells. These color-coded fibrosarcoma cell lines show similar cell proliferation and lung metastasis potential. The color-coded cells were mixed at a ratio of 1:1 and were injected into the tail vein of severe combined immunodeficient (SCID) mice. The resulting experimental lung metastases were simultaneously imaged and their ratio was determined by color-pixel analysis. Fluorescence color coding of cancer cells enables visualization of the interaction of cancer cells and can be used to distinguish cancer cells of any genotype or phenotype.

Nascent blood vessels in the skin arise from nestin-expressing hair-follicle cells

Besides forming hair shafts, the highly organized, metabolically vigorous hair follicle plays several crucial roles in skin architecture. The follicle contains a distinct population of presumptive follicular stem cells that express nestin, also a marker for neural stem cells. These nestin-expressing follicle cells are located principally in the follicular bulge region. Nestin-driven GFP (ND-GFP), transfected into mice, principally labels cells in the bulge region, which is consistent with the cells' being the stem cells of the hair follicle. We report here that ND-GFP also labels developing skin blood vessels that appear to originate from hair follicles and form a follicle-linking network. This is seen most clearly by transplanting ND-GFP-labeled vibrissa (whisker) hair follicles to unlabeled nude mice. New vessels grow from the transplanted follicle, and these vessels increase when the local recipient skin is wounded. The ND-GFP-expressing structures are blood vessels, because they display the characteristic endothelial-cell-specific markers CD31 and von Willebrand factor. This model displays very early events in skin angiogenesis and can serve for rapid antiangiogenesis drug screening.

An imageable highly metastatic orthotopic red fluorescent protein model of pancreatic cancer

In order to investigate the antitumor and antimetastatic efficacy of new chemotherapeutic agents, a novel, red-fluorescent, orthotopic model of pancreatic cancer was constructed in nude mice. MIA-PaCa-2 human pancreatic cancer cells were transduced with red fluorescent protein (RFP) and initially grown subcutaneously. Fluorescent tumor fragments were then transplanted onto the pancreas by surgical orthotopic implantation (SOI), facilitating high-resolution, real-time visualization of tumor and metastatic growth and dissemination in vivo. Tumor growth at the primary site was visible within the first postoperative week, while distant metastasis and the development of ascites became visible over the following week. This MIA-PaCa-2-RFP model produced extensive local disease and metastases to the retroperitoneum (100%), spleen (100%), intestinal and periportal lymph nodes (100%), liver (40%) and diaphragm (80%), and gave rise to malignant ascites and peritoneal carcinomatosis in 80% of cases. Growth and metastasis of tumor was more rapid and frequent than in previously described orthotopic pancreatic cancer models, leading to a median survival of only 21 days after tumor implantation. This unique, red fluorescent model rapidly and reliably simulates the highly aggressive course of human pancreatic cancer and can be easily non-invasively visualized in the live animal. The model can therefore be used for the discovery and evaluation of novel therapeutics for the treatment of this devastating disease.

The extracellular matrix differentially regulates the expression of PTHrP and the PTH/PTHrP receptor in FG pancreatic cancer cells

OBJECTIVES

Previous studies by our laboratory have demonstrated that parathyroid hormone-related protein (PTHrP) and its receptor (PTH/PTHrP receptor) are commonly expressed in pancreatic cancer and suggest their participation in the progression of this devastating disease. It has also been demonstrated that one of the major hallmarks of pancreatic adenocarcinoma is an increased production of the extracellular matrix (ECM), a critical regulator of diverse cellular processes such as differentiation, proliferation, and angiogenesis. The present study focused on the relationship between the PTHrP and ECM axes in the pathobiology of pancreatic cancer.

METHOD AND RESULTS

Using the FG pancreatic adenocarcinoma cell line, we demonstrate a significant inverse correlation between FG cell proliferation and PTHrP expression that depended on the ECM protein on which the cells were cultured (P < 0.05). Generally, ECM proteins that promoted the strongest proliferation, including type I collagen, type IV collagen, and laminin, resulted in decreased expression of PTHrP. Conversely, ECM proteins that promoted the weakest proliferation, including fibronectin, vitronectin, and BSA, resulted in increased expression of PTHrP. A similar trend was found between FG cell proliferation and the PTH/PTHrP receptor expression, with Pearson correlation coefficients of 0.480 (mRNA) and -0.591 (protein).

CONCLUSION

These observations demonstrate a unique functional relationship between the ECM and PTHrP axes and have important implications for our understanding of the complex mechanisms responsible for the progression of pancreatic cancer and its metastases.

Non-pancreatic periampullary adenocarcinomas: an explanation for favorable prognosis

BACKGROUND/AIMS

Our previous studies demonstrate that patients with non-pancreatic periampullary adenocarcinomas have a favorable prognosis relative to those with pancreatic adenocarcinoma. This study investigates histopathologic factors that contribute to the superior outcome of these patients.

METHODOLOGY

A retrospective review of all patients explored for periampullary neoplasms at a single institution over a 20-year period.

RESULTS

291 patients with periampullary neoplasms underwent exploratory laparotomy, of which 185 had resectable tumors. Periampullary adenocarcinomas were resected in 120: pancreatic head (n=74), distal common bile duct (n=10), duodenum (n=5), and ampulla of Vater (n=31). The resection rate for non-pancreatic adenocarcinomas was 90%, while that of pancreatic cancers was 44% (p<0.01). Median survival for resected non-pancreatic adenocarcinomas was 38.8 months; that of pancreatic tumors was 15.3 months (p<0.01). Non-pancreatic adenocarcinomas were significantly smaller (p<0.001), better differentiated (p<0.001), and less likely to have involved nodes (p<0.001), margins (p<0.001), perineural invasion (p<0.001), or vascular invasion (p<0.2) than pancreatic adenocarcinomas.

CONCLUSIONS

Histopathologic features of non-pancreatic periampullary adenocarcinomas significantly differentiate them from pancreatic adenocarcinoma and contribute to their relatively favorable long-term outcome following resection.

An imageable highly metastatic orthotopic red fluorescent protein model of pancreatic cancer

In order to investigate the antitumor and antimetastatic efficacy of new chemotherapeutic agents, a novel, red-fluorescent, orthotopic model of pancreatic cancer was constructed in nude mice. MIA-PaCa-2 human pancreatic cancer cells were transduced with red fluorescent protein (RFP) and initially grown subcutaneously. Fluorescent tumor fragments were then transplanted onto the pancreas by surgical orthotopic implantation (SOI), facilitating high-resolution, real-time visualization of tumor and metastatic growth and dissemination in vivo. Tumor growth at the primary site was visible within the first postoperative week, while distant metastasis and the development of ascites became visible over the following week. This MIA-PaCa-2-RFP model produced extensive local disease and metastases to the retroperitoneum (100%), spleen (100%), intestinal and periportal lymph nodes (100%), liver (40%) and diaphragm (80%), and gave rise to malignant ascites and peritoneal carcinomatosis in 80% of cases. Growth and metastasis of tumor was more rapid and frequent than in previously described orthotopic pancreatic cancer models, leading to a median survival of only 21 days after tumor implantation. This unique, red fluorescent model rapidly and reliably simulates the highly aggressive course of human pancreatic cancer and can be easily non-invasively visualized in the live animal. The model can therefore be used for the discovery and evaluation of novel therapeutics for the treatment of this devastating disease.

Dual-color fluorescence imaging distinguishes tumor cells from induced host angiogenic vessels and stromal cells

We have developed a simple yet powerful technique for delineating the morphological events of tumor-induced angiogenesis and other tumor-induced host processes with dual-color fluorescence. The method clearly images implanted tumors and adjacent stroma, distinguishing unambiguously the host and tumor-specific components of the malignancy. The dual-color fluorescence imaging is effected by using red fluorescent protein (RFP)-expressing tumors growing in GFP-expressing transgenic mice. This model shows with great clarity the details of the tumor-stroma interaction, especially tumor-induced angiogenesis and tumor-infiltrating lymphocytes. The GFP-expressing tumor vasculature, both nascent and mature, could be readily distinguished interacting with the RFP-expressing tumor cells. GFP-expressing dendritic cells were observed contacting RFP-expressing tumor cells with their dendrites. GFP-expressing macrophages were observed engulfing RFP-expressing cancer cells. GFP lymphocytes were seen surrounding cells of the RFP tumor, which eventually regressed. Dual-color fluorescence imaging visualizes the tumor-host interaction by whole-body imaging and at the cellular level in fresh tissues, dramatically expanding previous studies in fixed and stained preparations.

Determination of clonality of metastasis by cell-specific color-coded fluorescent-protein imaging

It has been thought that metastases are clonal and originate from rare cells in primary tumors that are heterogeneous in genotype and phenotype. Recent studies using DNA array analysis challenge this hypothesis and suggest the genetic background of the host is the important determinant of metastatic potential implying that metastases are not necessarily clonal. Previous methods to determine clonality of metastasis used karyotype or molecular analysis that were complicated, thereby limiting the number of metastatic colonies analyzed and the conclusions that could be drawn. We describe here the use of green fluorescent protein-labeled or red fluorescent protein-labeled HT-1080 human fibrosarcoma cells to determine clonality by simple fluorescence visualization of metastatic colonies after mixed implantation of the red and green fluorescent cells. Resulting pure red or pure green colonies were scored as clonal, whereas mixed yellow colonies were scored as nonclonal. In a spontaneous metastasis model originating from footpad injection in severe combined immunodeficient mice, 95% of the resulting lung colonies were either pure green or pure red, indicating monoclonal origin, whereas 5% were of mixed color, indicating polyclonal origin. In an experimental lung metastasis model established by tail vein injection in severe combined immunodeficient mice, clonality of lung metastasis was dependent on cell number. With a minimum cell number injected, almost all (96%) colonies were pure red or green and therefore monoclonal. When a large number of cells were injected, almost all (87%) colonies were mixed color and therefore heteroclonal. We conclude that spontaneous metastasis may be clonal because they are rare events, thereby supporting the rare-cell clonal origin of metastasis hypothesis. The clonality of the experimental metastasis model depended on the number of input cells. The simple fluorescence method of determining clonality of metastases described here can allow large-scale clonal analysis in numerous types of metastatic models.

Ampullary pancreatoblastoma in an elderly patient: a case report and review of the literature

Pancreatoblastoma, generally regarded as a pediatric malignant tumor, is rarely found in the adult population. Only 13 adults with pancreatoblastoma, ranging in age from 19 to 68 years, have previously been reported in the world literature. A diagnosis of pancreatoblastoma relies on characteristic histologic features, including epithelial differentiation and, more importantly, squamoid differentiation. Despite aggressive therapy, adults with pancreatoblastoma have a poor outcome. We describe a 78-year-old woman who presented with painless jaundice and was found on abdominal computed tomographic scan to have a 2.7-cm ampullary mass. The patient underwent successful pancreaticoduodenectomy. Pathologic examination of the resected tumor revealed findings characteristic of pancreatoblastoma. The tumor formed acinar and glandular structures, solid areas, and contained many "squamoid corpuscles," a defining feature of pancreatoblastoma. The tumor cells also showed acinar and ductal phenotype by immunohistochemistry. To the best of our knowledge, this case represents the oldest patient with pancreatoblastoma to be described in the literature to date and the first to occur in the ampulla of Vater. We review previously published cases and discuss the clinical and histopathologic features of adult pancreatoblastoma.

Gene therapy of pancreatic cancer with green fluorescent protein and tumor necrosis factor-related apoptosis-inducing ligand fusion gene expression driven by a human telomerase reverse transcriptase promoter

BACKGROUND

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) induces apoptosis in malignant cells but not in normal cells. Ad/g-TRAIL, an adenoviral vector in which expression of green fluorescent protein (GFP) and TRAIL is driven by a human telomerase reverse transcriptase promoter, has shown promise as a targeted antitumor agent.

METHODS

To investigate the effects of TRAIL gene therapy on pancreatic cancer, BxPC-3, MIA-PaCa-2, Panc-1, and ASPC-1 cells were treated with Ad/g-TRAIL. Transfection and protein expression were determined by using immunoblotting and identification of GFP with fluorescent microscopy and flow cytometry. Cell viability was determined by proliferation assay. Cell-cycle analysis and quantification of caspase-3 were used to identify apoptosis. The in vivo efficacy of Ad/g-TRAIL was characterized in a novel red fluorescent protein murine model of MIA-PaCa-2 pancreatic cancer.

RESULTS

Cells treated with Ad/g-TRAIL expressed GFP and exhibited apoptotic morphology within 2 days of treatment. Treatment with this vector in vitro resulted in less cell viability, increased caspase-3 activity, and a greater apoptotic fraction than treatment with controls. In vivo, treatment with Ad/g-TRAIL significantly suppressed tumor growth.

CONCLUSIONS

TRAIL gene therapy induces apoptosis of pancreatic tumor cells both in vitro and in vivo and is a promising therapy in the treatment of pancreatic cancer.

A novel red fluorescent protein orthotopic pancreatic cancer model for the preclinical evaluation of chemotherapeutics

BACKGROUND

Realistic models of pancreatic cancer are necessary to develop effective drugs for the disease. More aggressive tumor models enhanced by brighter fluorescent biomarkers to follow the disease in real time would enhance the ability to predict accurately the effect of novel therapeutics on this particularly malignant human cancer.

MATERIALS AND METHODS

A novel, highly fluorescent, red fluorescent protein (RFP)-expressing pancreatic cancer model was orthotopically established in nude mice. The MIA-PaCa-2 human pancreatic cancer cell line was transduced with RFP and grown subcutaneously. Fluorescent tumor fragments were then surgically transplanted onto the nude mouse pancreas. Groups treated with intraperitoneal gemcitabine or intravenous irinotecan were sequentially imaged to compare, in real time, the antimetastatic and antitumor effects of these agents compared with untreated controls.

RESULTS

Rapid tumor growth and widespread metastases developed in untreated mice within 2 weeks, leading to a median survival of 21 days. In contrast, significant tumor growth suppression and consequent increase in survival (32.5 days, P = 0.009) were achieved with CPT-11. Gemcitabine highly improved survival (72 days, P = 0.004) by inducing transient tumor regression over the first 3 weeks. However, at this time, growth and dissemination occurred despite continued treatment, suggesting the development of tumor resistance. The antimetastatic efficacy of each drug was followed noninvasively in real time by imaging the RFP-expressing tumor and metastases, and was confirmed by fluorescent open imaging of autopsy specimens.

CONCLUSIONS

This highly metastatic model reliably simulates the aggressive course of human pancreatic cancer. Noninvasive, sequential imaging permits quantification of tumor growth and dissemination and, thereby, real time evaluation of therapeutic efficacy. These features make this model an ideal, preclinical system with which to study novel therapeutics for pancreatic cancer.

Methioninase gene therapy with selenomethionine induces apoptosis in bcl-2-overproducing lung cancer cells

We have previously shown that the toxic pro-oxidant methylselenol is released from selenomethionine (SeMET) by cancer cells transformed with the adenoviral methionine alpha,gamma-lyase (methioninase, MET) gene cloned from Pseudomonas putida. Methylselenol damaged the mitochondria via oxidative stress, and caused cytochrome c release into the cytosol thereby activating caspase enzymes and thereby apoptosis. However, gene therapy strategies are less effective if tumor cells overexpress the antiapoptotic mitochondrial protein bcl-2. In this study, we investigated whether rAdMET/SeMET was effective against bcl-2-overproducing A549 lung cancer cells. We established two clones of the human lung cancer A549 cell line that show moderate and high expression levels of bcl-2, respectively, compared to the parent cell line, which has very low bcl-2 expression. Staurosporine-induced apoptosis was inhibited in the bcl-2-overproducing clones as well as in the parental cell line. In contrast to staurosporine, apoptosis was induced in the bcl-2-overproducing clones as well as the parental cell line by AdMET/SeMET. Apoptosis in the rAdMET-SeMET-treated cells was determined by fragmentation of nuclei, and release of cytochrome c from mitochondria to the cytosol. A strong bystander effect of AdMET/SeMET was observed on A549 cells as well as the bcl-2-overproducing clones. rAdMET/SeMET prodrug gene therapy is therefore a promising novel strategy effective against bcl-2 overexpression, which has blocked other gene therapy strategies.

Real-time GFP imaging of spontaneous HT-1080 fibrosarcoma lung metastases

Metastasis to the lung is often a lethal event in sarcoma as well as other cancers. We report here a new animal model of sarcoma enabling the external real-time fluorescence imaging of spontaneous lung metastasis. The human fibrosarcoma cell line HT-1080 was transduced with the green fluorescent protein (GFP) gene. HT-1080-GFP cells were injected into the right hind footpad of severe combined immunodeficient (SCID) mice. The lung metastases were evaluated by whole-body fluorescence imaging as well as direct-view imaging in live animals through a skin-flap window over the chest wall. Spontaneous lung metastases were observed on the lungs of 11 of 12 mice. SCID mice well tolerated the skin-flap procedure enabling real-time imaging of spontaneous lung metastases with a resolution of approximately 50-100 microm. This procedure enabled external imaging at the micrometastasis level. Real-time evaluation of spontaneous lung metastasis in the same animals should allow drug evaluation and mechanistic studies not previously possible.

Combination efficacy of doxorubicin and adenoviral methioninase gene therapy with prodrug selenomethionine

We have previously demonstrated an enzyme activation prodrug gene therapy strategy using the methionine alpha,gamma-lyase gene (MET) cloned from Pseudomonas putida, in combination with selenomethionine (SeMET) as a prodrug. MET gene transfer via a recombinant adenovirus (Ad-MET) converts the physiologic compound SeMET to highly toxic methylselenol. In this study, we have developed a combination therapy approach using Ad-MET/SeMET gene therapy and doxorubicin (DOX). The combination significantly delayed the growth of H460, an aggressively-growing human lung cancer cell line, in nude mice. H460 cells were injected intra-dermally in nude mice. Tumor-bearing mice were divided into 12 groups [Control (Ctrl), DOX, SeMET, SeMET + DOX, Ad-Ctrl, Ad-Ctrl + SeMET, Ad-Ctrl + DOX, Ad-Ctrl + SeMET + DOX, Ad-MET, Ad-MET + DOX, Ad-MET + SeMET, and Ad-MET + SeMET + DOX]. DOX (2 mg/kg body weight) was given intra-peritoneally twice at 7-day intervals. SeMET (1 microM/mouse) was given by intra-tumor injection everyday, starting the following day after transfection with adenovirus. Tumor growth in the untreated group showed a 10-fold increase in tumor volume after two weeks. In contrast, the increase was only 2.5-fold in the DOX + Ad-MET/SeMET group. The treatment with DOX alone at the low-dose used showed no effect compared to the control group. There was a 5.8-fold increase in tumor volume in mice treated with Ad-MET/SeMET gene therapy alone. The tumor doubling-time was increased to approximately 10 days with the combination therapy of Ad-MET + SeMET + DOX as opposed to 2-3 days in all other treatment groups.

Real-time imaging of individual fluorescent-protein color-coded metastatic colonies in vivo

We have established stable, bright green fluorescent protein (GFP)- or red fluorescent protein (RFP)-expressing HT-1080 human fibrosarcoma clones. These cell lines showed similar cell proliferation rates and high-frequency experimental lung metastasis. The HT-1080-GFP and -RFP clones enable simultaneous real-time dual-color imaging in the live animal. HT-1080 cells were transduced with retroviral vectors containing GFP or RFP and the neomycin resistance gene. Stable transformants were selected stepwise with G418 up to 800 microl/ml. Subsequently, high GFP- or RFP-expressing clones, HT-1080-GFP or HT-1080-RFP, respectively, were selected. 3 x 10(6) cells from each clone were mixed and injected into the tail vein of SCID mice. The cells seeded the lung at high frequency with subsequent formation of pure green and pure red colonies as well as mixed yellow colonies with different patterns visualized directly on excised lungs. The lung metastases were also visualized by external fluorescence imaging in live animals through skin-flap windows over the chest wall. Lung metastases were observed on the lung surface of all mice. SCID mice well tolerated multiple surgical procedures for direct-view imaging via skin-flap windows. Real-time metastatic growth of the two different colored clones in the same lung was externally imaged with resolution and quantification of green, red, or yellow colonies in live animals. The color coding enabled determination of whether the colonies grew clonally or were seeded as a mixture with one cell type eventually dominating, or whether the colonies grew as a mixture. The simultaneous real-time dual-color imaging of metastatic colonies described in this report gives rise to the possibility of color-coded imaging of clones of cancer cells carrying various forms of gene of interest.

Bax-induction gene therapy of pancreatic cancer

BACKGROUND

Bax is a strong pro-apoptotic gene that induces programmed cell death when expressed. Human telomerase reverse transcriptase (hTERT) is the catalytic subunit for telomerase, an enzyme found to be active in more than 85% of human cancers. Recently, a binary adenoviral system (Ad/GT-Bax + Ad/hTERT-GV16) was constructed using the hTERT promoter to induce Bax gene expression in tumor cells.

METHODS

To test whether human pancreatic tumor cells would respond to this system of Bax-induced apoptosis, we compared the effects of Bax gene induction with that of LacZ gene induction using the same binary system.

RESULTS

Lysates of the human pancreatic cell lines PANC-28, MIA PaCa-2, and BxPC-3 showed significantly elevated levels of human telomerase using the PCR-based TRAP assay. As early as 24 h after treatment with Bax-induction gene therapy, growth inhibition was observed. Overexpression of the Bax protein was confirmed by Western blotting. Extensive apoptosis on FACS analysis at 48 h was seen after Bax induction. In addition, cytosolic cytochrome c levels increased compared to mitochondrial levels after Bax induction. Levels of caspase-3, a key downstream enzyme involved in apoptosis, also increased significantly compared to controls after treatment. None of these effects were seen with LacZ.

CONCLUSION

Our results suggest that the binary adenoviral vector system, Ad/GT-Bax + Ad/hTERT-GV16, induces high levels of Bax expression that induce apoptosis in human pancreatic cancer cells.

Optically imageable metastatic model of human breast cancer

We report an optically imageable orthotopic metastatic nude mouse model of the human breast cancer MDA-MB-435 expressing green fluorescent protein (GFP). We demonstrate fluorescent imaging of primary and metastatic growth in live tissue and in intact animals. Fragments of tumor tissue expressing GFP were sutured into the pocket in the right second mammary gland. Tumor tissue was strongly fluorescent, enabling whole-body imaging of tumor growth by week 5. Neovascularization of the primary tumor was also visualized by whole-body imaging by contrast of the vessels to the fluorescent tumor. At autopsy, the MDA-MB-435-GFP was found to have metastasized to various organs, including the lung in 55% of the animals, the lymph nodes in 15% of the animals including axillary nodes, and the liver in 10% of the animals. These metastases could be visualized in fresh tissue by fluorescent imaging. Detailed fluorescence analysis visualized extensive metastasis in the thoracic cavity and the lymphatic system. Large metastatic nodules in the lung involved most of the pulmonary parenchyma in all lobes. Lymph node metastasis was found mainly in the axillary area. In the liver, fluorescent macroscopic metastatic nodules were found under the capsule. The metastatic pattern in the model thus reflected clinical metastatic breast cancer and provides a powerful model for drug discovery for this disease.

Parathyroid hormone-related protein as a novel tumor marker in pancreatic adenocarcinoma

INTRODUCTION

Parathyroid hormone-related protein (PTHrP) can act as an oncoprotein to regulate the growth and proliferation of many common malignancies, including pancreatic cancer. Previous studies have shown that PTHrP is produced by human pancreatic cancer cell lines, can be shown in the cytoplasm and nucleus of paraffin-embedded pancreatic adenocarcinoma tumor specimens, and is secreted into the media of cultured pancreatic adenocarcinoma cells. We hypothesized that PTHrP could serve as a tumor-marker for growth of pancreatic cancer in vivo.

AIM AND METHODOLOGY

To test this hypothesis, we used an orthotopic model developed in our laboratory of the PTHrP-producing human pancreatic cancer line, BxPC-3. This tumor was stably transduced with green fluorescence protein (GFP) to facilitate visualization of tumor growth and metastases. At early (5 weeks) and late (13 weeks) time points after surgical orthotopic implantation, serum PTHrP was measured and primary and metastatic tumor burden was determined for each mouse by assessing GFP expression.

RESULTS

By 5 weeks after surgical orthotopic implantation (early group), the mean serum PTHrP level was 33.3 pg/mL. In contrast, by 13 weeks after surgical orthotopic implantation (late group), the mean serum PTHrP level increased to 158.5 pg/mL. These differences were highly significant (p < 0.001, Student t test). Numerous metastatic lesions were readily visualized by GFP in the late group. Serum PTHrP levels measured by immunoassay correlated with primary pancreatic tumor weights and serum calcium levels (p <0.01). PTHrP levels were not detectable (<21 pg/mL) in any of the 10 control mice with no tumor. Western blotting of BxPC-3-GFP tumor lysates confirmed the presence of PTHrP. BxPC-3-GFP tumor tissue stained with antibody to PTHrP.

CONCLUSION

These results indicate that PTHrP can serve as a tumor marker in animal models of pancreatic cancer and may be a useful tumor marker for clinical pancreatic adenocarcinoma.

Direct external imaging of nascent cancer, tumor progression, angiogenesis, and metastasis on internal organs in the fluorescent orthotopic model

Mouse tumor models have undergone profound improvements in the fidelity of emulating human disease. Replacing ectopic s.c. implantation with organ-specific orthotopic implantation reproduces human tumor growth and metastasis. Strong fluorescent labeling with green fluorescent protein along with inexpensive video detectors, positioned externally to the mouse, allows the monitoring of details of tumor growth, angiogenesis, and metastatic spread. However, the sensitivity of external imaging is limited by light scattering in intervening tissue, most especially in skin. Opening a reversible skin-flap in the light path markedly reduces signal attenuation, increasing detection sensitivity many-fold. The observable depth of tissue is thereby greatly increased and many tumors that were previously hidden are now clearly observable. This report presents tumor images and related quantitative growth data previously impossible to obtain. Single tumor cells, expressing green fluorescent protein, were seeded on the brain image through a scalp skin-flap. Lung tumor microfoci representing a few cells are viewed through a skin-flap over the chest wall, while contralateral micrometastases were imaged through the corresponding skin-flap. Pancreatic tumors and their angiogenic microvessels were imaged by means of a peritoneal wall skin-flap. A skin-flap over the liver allowed imaging of physiologically relevant micrometastases originating in an orthotopically implanted tumor. Single tumor cells on the liver arising from intraportal injection also were detectable. Possible future technical developments are suggested by the image, through a lower-abdominal skin-flap, of an invasive prostate tumor expressing both red and green fluorescent proteins in separate colonies.

Real-time optical imaging of primary tumor growth and multiple metastatic events in a pancreatic cancer orthotopic model

We report here whole-body optical imaging, in real time, of genetically fluorescent pancreatic tumors growing and metastasizing to multiple sites in live mice. The whole-body optical imaging system is external and noninvasive. Human pancreatic tumor cell lines, BxPC-3 and MiaPaCa-2, were engineered to stably express high-levels of the Aequorea victoria green fluorescent protein (GFP). The GFP-expressing pancreatic tumor cell lines were surgically orthotopically implanted as tissue fragments in the body of the pancreas of nude mice. Whole-body optical images visualized real-time primary tumor growth and formation of metastatic lesions that developed in the spleen, bowel, portal lymph nodes, omentum, and liver. Intravital images in the opened animal confirmed the identity of whole-body images. The whole-body images were used for real-time, quantitative measurement of tumor growth in each of these organs. Intravital imaging was used for quantification of growth of micrometastasis on the liver and stomach. Whole-body imaging was carried out with either a trans-illuminated epi-fluorescence microscope or a fluorescence light box, both with a thermoelectrically cooled color CCD camera. The simple, noninvasive, and highly selective imaging made possible by the strong GFP fluorescence allowed detailed simultaneous quantitative imaging of tumor growth and multiple metastasis formation of pancreatic cancer. The GFP imaging affords unprecedented continuous visual monitoring of malignant growth and spread within intact animals without the need for anesthesia, substrate injection, contrast agents, or restraint of animals required by other imaging methods. The GFP imaging technology presented in this report will facilitate studies of modulators of pancreatic cancer growth, including inhibition by potential chemotherapeutic agents.

Methioninase cancer gene therapy with selenomethionine as suicide prodrug substrate

In this study, we report a novel approach to gene-directed enzyme prodrug therapy for cancer. This gene therapy strategy exploits the toxic pro-oxidant property of methylselenol, which is released from selenomethionine (SeMET) by cancer cells with the adenoviral-delivered methionine alpha,gamma-lyase (MET) gene cloned from Pseudomonas putida. In MET-transduced tumor cells, the cytotoxicity of SeMET is increased up to 1000-fold compared with nontransduced cells. A strong bystander effect occurred because of methylselenol release from MET gene-transduced cells and uptake by surrounding tumor cells. Methylselenol damaged the mitochondria via oxidative stress and caused cytochrome c release into the cytosol, thereby activating the caspase cascade and apoptosis. Adenoviral MET-gene/SeMET treatment also inhibited tumor growth in rodents and significantly prolonged their survival. Recombinant adenovirus-encoding MET gene-SeMET treatment thereby offers a new paradigm for cancer gene therapy.

Rectal excision with coloanal anastomosis for superficial distal third rectal cancer: survival and local recurrence

OBJECTIVE

Appropriate surgical treatment of distal third rectal cancer limited to bowel wall (i.e. T1 or T2) in medically operable patients is controversial. Transanal excision can deprive some patients of accurate pathological staging, prognosis and cure. In contrast abdominoperineal resection has considerable practical and psychosocial problems largely related to a permanent colostomy. We hypothesize that superficial distal rectal tumours can be effectively treated with rectal excision and coloanal anastomosis.

SUBJECTS AND METHODS

Prospective oncological study of 80 patients with distal third superficial rectal carcinomas treated by complete rectal excision with coloananl anastomosis from December 1977 to January 1993 was carried out. The resected specimens were examined for depth of spread and number of histologically positive nodes. The actuarial local recurrence and survival rates for superficial node-negative and node-positive tumours were analysed independently.

RESULTS

Seventy-eight patients had complete postoperative assessment. Thirty-one percent had received low-dose preoperative neo-adjuvant radiotherapy (3500 rads). Mean follow-up time in all patients was 70 months on average. The lymph node involvement rate for T1 and T2 tumours was 12.5 and 15.6%, respectively. The local recurrence rates for patients with (T1/T2) N0 and (T1/T2) N1 were 1.5 and 16.7%, respectively, and the five year actuarial survival rates were 96.6 and 90%, respectively. The overall local recurrence was 3.8% with five-year actuarial survival of 95.8%.

CONCLUSIONS

Lymph node involvement in superficial tumours is not rare. Rectal excision with coloanal anastomosis results in a high cure rate especially for node-positive superficial tumours. This treatment strategy avoids the psychological trauma of colostomy following abdominoperineal resection and the potential risk of undertreatment by local excision.

Spatial-temporal imaging of bacterial infection and antibiotic response in intact animals

We describe imaging the luminance of green fluorescent protein (GFP)-expressing bacteria from outside intact infected animals. This simple, nonintrusive technique can show in great detail the spatial-temporal behavior of the infectious process. The bacteria, expressing the GFP, are sufficiently bright as to be clearly visible from outside the infected animal and recorded with simple equipment. Introduced bacteria were observed in several mouse organs including the peritoneal cavity, stomach, small intestine, and colon. Instantaneous real-time images of the infectious process were acquired by using a color charge-coupled device video camera by simply illuminating mice at 490 nm. Most techniques for imaging the interior of intact animals may require the administration of exogenous substrates, anesthesia, or contrasting substances and require very long data collection times. In contrast, the whole-body fluorescence imaging described here is fast and requires no extraneous agents. The progress of Escherichia coli-GFP through the mouse gastrointestinal tract after gavage was followed in real-time by whole-body imaging. Bacteria, seen first in the stomach, migrated into the small intestine and subsequently into the colon, an observation confirmed by intravital direct imaging. An i.p. infection was established by i.p. injection of E. coli-GFP. The development of infection over 6 h and its regression after kanamycin treatment were visualized by whole-body imaging. This imaging technology affords a powerful approach to visualizing the infection process, determining the tissue specificity of infection, and the spatial migration of the infectious agents.

Antimetastatic efficacy of adjuvant gemcitabine in a pancreatic cancer orthotopic model

Gemcitabine is a promising new agent that has been recently studied for palliation of advanced (stage IV) unresectable pancreatic cancer. We hypothesized that adjuvant gemcitabine would reduce recurrence and metastases following surgical resection of pancreatic cancer. To test this hypothesis, we evaluated gemcitabine on a green fluorescent protein (GFP) transductant of the human pancreatic cancer cell line BxPC-3 (BxPC-3-GFP) using surgical orthotopic implantation (SOI) in nude mice. GFP enabled high resolution fluorescent visualization of primary and metastatic growth. Five weeks after SOI, the mice were randomized into three groups: Group I received exploratory laparotomy only. Group II underwent surgical resection of the pancreatic tumor without further treatment. Group III underwent tumor resection followed by adjuvant treatment with gemcitabine, 100 mg/kg every three days for a total of four doses, starting two days after resection. The mice were sacrificed at thirteen weeks following implantation and the presence and location of recurrent tumor was recorded. Gemcitabine reduced the recurrence rate to 28.6% compared to 70.6% with resection only (P = 0.02) and reduced metastatic events 58% in the adjuvant group compared to resection only. This study, demonstrating that gemcitabine is effective as adjuvant chemotherapy post-pancreatectomy, suggests this new indication of the drug clinically.

Chronologically-specific metastatic targeting of human pancreatic tumors in orthotopic models

Pancreatic cancer is a highly metastatic disease that responds poorly to currently-available treatment. In order to better visualize and understand the chronology and specificity of metastatic targeting of pancreatic cancer, two human pancreatic cancer cell lines, expressing green fluorescent protein (GFP), were studied in orthotopic models. MIA-PaCa2-GFP and BxPC-3-GFP tumor fragments were transplanted by surgical orthotopic implantation (SOI) to the nude mouse pancreas for fluorescence visualization of the chronology of pancreatic tumor growth and metastatic targeting. BxPC-3-GFP tumors developed rapidly in the pancreas and spread regionally to the spleen and retroperitoneum as early as six weeks. Distant metastases in BxPC-3-GFP were rare. In contrast, MIA-PaCa-2-GFP grew more slowly in the pancreas but rapidly metastasized to distant sites including liver and portal lymph nodes. Regional metastases in MIA-PaCa-2-GFP were rare. These studies demonstrate that pancreatic cancers have highly specific and individual 'seed-soil' interactions governing the chronology and sites of metastatic targeting.

A highly metastatic Lewis lung carcinoma orthotopic green fluorescent protein model

The Lewis lung carcinoma has been widely used for many important studies. However, the subcutaneous transplant or orthotopic cell-suspension injection models have not allowed the expression of its full metastatic potential. A powerful new highly metastatic model of the widely-used Lewis lung carcinoma is reported here using surgical orthotopic implantation (SOI) of tumor fragments and enhanced green fluorescent protein (GFP) transduction of the tumor cells. To achieve this goal, we first developed in vitro a stable high-expression GFP transductant of the Lewis lung carcinoma with the pLEIN retroviral expression vector containing the enhanced Aequorea victoria GFP gene. Stable high-level expression of GFP was found maintained in vivo in subcutaneously-growing Lewis lung tumors. The in vivo GFP-expressing tumors were harvested and implanted as tissue fragments by SOI in the right lung of additional nude mice. This model resulted in rapid orthotopic growth and extensive metastasis visualized by GFP-expression. 100% of the animals had metastases on the ipsilateral diaphragmatic surface, contralateral diaphragmatic surface, contralateral lung parenchima, and in mediastinal lymph nodes. Heart metastases were visualized in 40%, and brain metastases were visualized in 30% of the SOI animals. Mice developed signs of respiratory distress between 10-15 days post-tumor implantation and were sacrificed. The use of GFP-transduced Lewis lung carcinoma transplanted by SOI reveals for the first time the high malignancy of this tumor and provides an important useful model for metastasis, angiogenesis and therapeutic studies.

Whole-body and intravital optical imaging of angiogenesis in orthotopically implanted tumors

The development of drugs for the control of tumor angiogenesis requires a simple, accurate, and economical assay for tumor-induced vascularization. We have adapted the orthotopic implantation model to angiogenesis measurement by using human tumors labeled with Aequorea victoria green fluorescent protein for grafting into nude mice. The nonluminous induced capillaries are clearly visible against the very bright tumor fluorescence examined either intravitally or by whole-body luminance in real time. The orthotopic implantation model of human cancer has been well characterized, and fluorescence shadowing replaces the laborious histological techniques for determining blood vessel density. Intravital images of orthotopically implanted human pancreatic tumors clearly show angiogenic capillaries at both primary and metastatic sites. A quantitative time course of angiogenesis was determined for an orthotopically growing human prostate tumor periodically imaged intravitally in a single nude mouse over a 19-day period. Whole-body optical imaging of tumor angiogenesis was demonstrated by injecting fluorescent Lewis lung carcinoma cells into the s.c. site of the footpad of nude mice. The footpad is relatively transparent, with comparatively few resident blood vessels, allowing quantitative imaging of tumor angiogenesis in the intact animal. Capillary density increased linearly over a 10-day period as determined by whole-body imaging. Similarly, the green fluorescent protein-expressing human breast tumor MDA-MB-435 was orthotopically transplanted to the mouse fat pad, where whole-body optical imaging showed that blood vessel density increased linearly over a 20-week period. These powerful and clinically relevant angiogenesis mouse models can be used for real-time in vivo evaluation of agents inhibiting or promoting tumor angiogenesis in physiological microenvironments.

Efficacy of intra-hepatectomy 5-FU on recurrence and metastasis of human hepatocellular carcinoma in nude mice

A novel intra-operative chemotherapy nude mouse model for human hepatocellular carcinoma (HCC) has been developed. Intra-peritoneal (i.p.) administration of 5-fluorouracil (5-FU) was begun 2 hr before hepatic resection of HCC and then continued post-operatively for 4 consecutive days. This regime, termed intra-hepatectomy chemotherapy (IHC), significantly prolonged animal survival compared with pre-operative 5-FU, neoadjuvant therapy, 5-FU post-operative adjuvant therapy, surgery alone, 5-FU without surgery, and the untreated control. The median survival of the intra-operative 5-FU-treated group was 127 days compared with 78 days for the neoadjuvantly-treated animals and 53 days for the control group (p<0.006). When all animals with neoadjuvant 5-FU treatment had died, 60% of the animals in the IHC group were still alive (p<0.011). Survival of all other treatment groups, including 5-FU without surgery, surgery alone, and adjuvant post-operative chemotherapy, was not significantly different from the untreated control group. Five animals in the IHC group were free of tumor when sacrificed at day 150 post-surgically. While 100% of animals in the control group had lymph nodes draining the liver involved with metastases, only 20% of animals in the IHC group had lymph node metastases. These data suggested that IHC therapy increased survival by preventing metastases of cancer cells not removed in the liver resection procedure. The results of this study indicate that IHC therapy for resection of HCC should be investigated clinically.

Human pancreatic adenocarcinomas express parathyroid hormone-related protein

PTH-related protein (PTHrP) is expressed in many common malignancies such as breast and prostate cancer and can regulate their growth. Little is known, however, about the role of PTHrP in pancreatic adenocarcinoma. To study PTHrP in pancreatic exocrine cancer, we studied its expression in pancreatic cancer cell lines and surgical specimens. Eight human pancreatic adenocarcinoma cell lines were evaluated: AsPC-1, BxPC-3, Capan-1, CFPAC-1, MIA PaCa-2, PANC-1, PANC-28, and PANC-48. Murine monoclonal antibodies to the amino-terminal (1-34), mid-region (38-64), and carboxyl-terminal peptides (109-141) of PTHrP were used to identify cellular PTHrP and secreted PTHrP, including Western blotting and immunocytochemical staining for PTHrP from each cell line. Cellular PTHrP was detected in all cell line extracts by both Western blotting and immunoassay. CFPAC-1, derived from a pancreatic liver metastasis, had the highest concentration of PTHrP, and MIA PaCa-2, derived from primary pancreatic adenocarcinoma, had the lowest. PTHrP was localized by immunocytochemical staining in the cytoplasm in all but one cell line, and both nuclear and cytoplasmic immunostaining were observed in the MIA PaCa-2 and PANC-1 cells. Secretion of PTHrP into cell medium was also observed for each cell line and paralleled intracellular PTHrP levels. Evidence for differential processing of PTHrP expression was provided by studies demonstrating different patterns of PTHrP among the cell lines when assessed by PTHrP immunoassays directed against different PTHrP peptides. In specific, PTHrP secretion measured by a PTHrP-(38-64) assay was highest for BxPC-3, whereas the highest levels of secreted PTHrP-(109-141) occurred in CFPAC-1 and PANC-1. Growth of AsPC-1 cells was stimulated in a dose-dependent manner by PTHrP-(1-34). Immunostaining from archival tissue of patients with pancreatic adenocarcinoma revealed strong PTHrP expression in all 14 specimens. All patients were eucalcemic preoperatively. These results demonstrate that PTHrP is commonly expressed in pancreatic cancer. Our data suggest that PTHrP may have growth-regulating properties in pancreatic adenocarcinoma cells, but further studies are required.

Visualizing gene expression by whole-body fluorescence imaging

Transgene expression in intact animals now can be visualized by noninvasive techniques. However, the instruments and protocols developed so far have been formidable and expensive. We describe here a system for rapidly visualizing transgene expression in major organs of intact live mice that is simple, rapid, and eminently affordable. Green fluorescent protein (GFP) is expressed in the cells of brain, liver, pancreas, prostate, and bone, and its fluorescence is encoded in whole-body optical images. For low-magnification images, animals are illuminated atop a fluorescence light box and directly viewed with a thermoelectrically cooled color charge-coupled device camera. Higher-magnification images are made with the camera focused through an epi-fluorescence dissecting microscope. Both nude and normal mice were labeled by directly injecting 8 x 10(10) plaque-forming units/ml of adenoviral GFP in 20-100 microl PBS and 10% glycerol into either the brain, liver, pancreas, prostate, or bone marrow. Within 5-8 h after adenoviral GFP injection, the fluorescence of the expressed GFP in brain and liver became visible, and whole-body images were recorded at video rates. The GFP fluorescence continued to increase for at least 12 h and remained detectable in liver for up to 4 months. The system's rapidity of image acquisition makes it capable of real-time recording. It requires neither exogenous contrast agents, radioactive substrates, nor long processing times. The method requires only that the expressed gene or promoter be fused or operatively linked to GFP. A comparatively modest investment allows the study of the therapeutic and diagnostic potential of suitably tagged genes in relatively opaque organisms.

In vivo tumor delivery of the green fluorescent protein gene to report future occurrence of metastasis

The green fluorescent protein (GFP) gene was administered to intraperitoneally (i.p.) growing human stomach cancer in nude mice to visualize future regional and distant metastases. GFP retroviral supernatants were injected i.p. from day 4 to day 10 after i.p. implantation of the cancer cells. Tumor and metastasis fluorescence was visualized every other week with the use of fluorescence optics via a laparotomy on the tumor-bearing animals. At 2 weeks after retroviral GFP delivery, GFP-expressing tumor cells were observed in gonadal fat, greater omentum, and intestine, indicating that these primary i.p. growing tumors were efficiently transduced by the GFP gene and could be visualized by its expression. At the second and third laparotomies, GFP-expressing tumor cells were observed to have spread to lymph nodes in the mesentery and other regional sites. At the fourth laparotomy, widespread tumor growth was visualized by GFP expression, inducing liver metastasis. No normal tissues were found to be transduced by the GFP retrovirus. Thus, reporter gene transduction of the primary tumor enabled detection of its subsequent metastasis. This gene therapy model could be applied to primary tumors before resection or other treatment to have a fluorescent early detection system for metastasis and recurrence.

Factors influencing survival after resection for periampullary neoplasms

BACKGROUND

The purpose of this study was to determine predictors of survival after resection for periampullary neoplasms.

METHODS

Over a 15-year period, 208 patients underwent laparotomy for periampullary neoplasms. Data were analyzed to assess predictors of survival.

RESULTS

Pathologic examination showed pancreatic cancer (n = 136; 65%), ampullary cancer (n = 28; 13%), distal common bile duct cancer (n = 10; 5%), duodenal cancer (n = 4; 2%), neuroendocrine tumor (n = 11; 5%), cystadenocarcinoma (n = 4; 2%), cystadenoma (n = 5; 2%), and other (n = 10; 5%). A total of 129 patients underwent pancreatic resection (71 Whipples, 35 total pancreatectomies, 21 distal pancreatectomies, and 2 partial pancreatectomies) whereas 79 patients were found to be unresectable and underwent palliative bypass and/or biopsy. Median survival was 20.4 months for resectable patients versus 4.5 months for unresectable patients (P<0.001). Of the 129 resected patients, factors significantly (P<0.05) favoring long-term survival on univariate analysis included well-differentiated histology, common bile duct or ampullary adenocarcinoma, early stage, tumor diameter <2 cm, negative margins, and absence of lymph node metastases, perineural, or vascular invasion. Age, sex, race, and type of procedure had no influence on survival. On multivariate analysis, only tumor differentiation appeared independently related to survival. Using Kendall's tau analysis, tumor type and grade correlated significantly with all other predictors.

CONCLUSIONS

Of all variables studied, tumor type and poor tumor differentiation in periampullary neoplasms appear to be markers that predict a constellation of other adverse findings.

An orthotopic mouse model of remetastasis of human colon cancer liver metastasis

Whether liver metastases from colon cancer are capable of metastasizing to other sites is an important question in surgical oncology. To answer this question, we have developed a highly metastatic orthotopic transplant model of a liver metastasis from a human colon cancer patient in nude mice that targets the liver and lymph nodes. The metastatic human tumor was transplanted in athymic nude mice by surgical orthotopic implantation (SOI) of a liver metastasis from a colon cancer patient. The human colon tumor was then subsequently implanted in the colon by SOI or, in an additional series of nude mice, in the liver by surgical hepatic implantation (SHI). The mice were then explored over time for lymph node involvement beginning 10 days after implantation. After SOI, 100% of the animals had liver metastasis within 10 days, and subsequently, 19 days after SOI, all lymph nodes draining the liver were involved with metastasis without any retroperitoneal or lung tissue involvement. After SHI, all sites of lymphatic drainage of the liver, including portal, celiac, and mediastinal lymph nodes, were massively involved by metastasis in 100% of the animals as early as 10 days after tumor implantation on the liver. The results of this study demonstrate that liver metastases from colon cancer are capable of remetastasizing to other sites. This study thus suggests that in colon cancer patients with liver metastasis, mediastinal, celiac, and portal lymph node metastases originate from the liver metastasis and not, as previously thought, from primary colon cancer.

Antimetastatic intraoperative chemotherapy of human colon tumors in the livers of nude mice

We have developed a new antimetastatic chemotherapeutic strategy for combination with hepatic resection of human colon cancers in a high-metastasis nude mouse model. The new procedure involves i.p. administration of 5-fluorouracil (5-FU) 2 h before hepatic resection of the human colon tumors, with therapy continued postoperatively for 4 consecutive days. We termed this strategy neo-neoadjuvant chemotherapy. The regime significantly prolonged animal survival compared with preoperative 5-FU neoadjuvant therapy, 5-FU postoperative adjuvant therapy, surgery alone, 5-FU without surgery, or the untreated control. The median survival of neo-neoadjuvant i.p. 5-FU-treated group was 81 days, compared with 27 days for the control group (P < 0.009). The median survival of animals in the neoadjuvant group was 37 days (P < 0.021 compared with the control group). There was also a significant difference between the median survival of neo-neoadjuvant, and the neoadjuvant group (P < 0.031). When all animals in the control group had died, 70% of animals with neo-neoadjuvant and 60% of animals with neoadjuvant 5-FU were still alive (P < 0.003 and P < 0.011, respectively). When all animals with neoadjuvant 5-FU treatment had died, 70% of animals with neo-neoadjuvant treatment were still alive (P < 0.003). Survival of all other treatment groups, including 5-FU without surgery, surgery alone, and adjuvant postoperative chemotherapy, was not significantly different from the untreated control group. Two animals in the neo-neoadjuvant group were free of tumors when sacrificed at days 154 and 165 post surgery. Whereas 100% of animals in the control, 90% in the 5-FU alone, 70% in the surgery alone, 60% in the 5-FU adjuvant, and 40% in the neoadjuvant groups had metastases in the lymph nodes draining the liver, only 10% of animals in the neo-neoadjuvant group had metastases. These data suggest that the neo-neoadjuvant therapy increased survival by preventing metastasis of cancer cells not removed in the liver resection procedure. The results of this study indicate that the neo-neoadjuvant treatment strategy for resection of colon cancer liver metastasis should be explored clinically.

Methioninase gene therapy of human cancer cells is synergistic with recombinant methioninase treatment

Results obtained over the past 40 years have demonstrated that tumor cells of all types tested have an elevated growth requirement for methioninase compared with normal cells. Recombinant methioninase (rMETase) cloned from Pseudomonas putida has been found previously to be an effective antitumor agent attributable to deprivation of the extracellular methionine source of the tumor. To degrade intracellular methioninase, we have now developed an adenoviral vector inserted with the P. putida methioninase (MET) gene (rAd-MET). The in vitro efficacy of rAd-MET was tested on the OVCAR-8 human ovarian cancer cell line, the HT1080 human fibrosarcoma cell line, and human normal fibroblasts. rAd-MET transduction of OVACAR-8 and HT1080 resulted in high levels of methioninase expression up to 10% or more of the total protein of the cells, depending on the multiplicity of infection. The IC50 of rAd-MET for OVCAR-8 cells in 96-well plates was approximately 2 x 106 plaque-forming units (pfu)/well. The IC50 of control adenovirus (control-rAd) was 4 x 10(7) pfu/well, 20 times higher than rAd-MET. In the presence of the IC50 of 2 x 10(6) pfu/well of rAd-MET, the addition of 0.025 units/ml of rMETase, which is 25% of the IC50, resulted in a 90% inhibition of tumor cell number. This indicated that rAd-MET enhanced the efficacy of rMETase. In contrast, 2 x 10(6) pfu/well of control-rAd in combination with 0.025 units/ml of rMETase had an efficacy of only 10% inhibition of cell number. The synergistic effect of the combination of rMETase and rAd-MET was quantitated by calculating the combination index (CI). The CIs for all combinations of rAd-MET and rMETase tested on OVCAR-8 were <0.7 with a mean of 0.5, indicating synergy. Similar synergy of rAd-MET and rMETase was seen on HT1080 human fibrosarcoma cells with a mean of 0.74. In contrast, the CIs of all combinations of rMETase and control adenovirus concentrations tested on both cell lines had a mean CI of approximately 1, which indicated that this combination had only an additive effect. The normal fibroblasts, on the other hand, appeared relatively resistant to the MET gene because in the presence of rMETase, 2.5 x 10(7) pfu/well of rAd-MET or control rAd had almost an identical effect on cell survival. The selectively strong synergy of rAd-MET and rMETase on cancer cells allows reduced levels of each agent to be used, thus decreasing potential side effects.